London , England -LRB- CNN -RRB- -- Nearly two decades after the killing of toddler James Bulger by two 10-year-old boys in a suburb of Liverpool , what remains one of Britain 's most notorious child murders this week proved once again it has the power to shock and outrage .

Seen at the time as symbolic of a flawed society , the killing of Bulger -- whose poignant last moments being led to his death were caught by security camera -- continues to be dissected by a country still struggling to comprehend the crime .

This came to a head nine years ago when British authorities provoked anger by releasing the killers , Robert Thompson and Jon Venables , just eight years into the life sentences they received for attacking and torturing Bulger and dumping his battered body on a railway track .

And the fury resurfaced this week with confirmation that one of the two boys , Jon Venables , now a 27-year-old man , was placed back in police custody after breaching the conditions of his release .

The pair were jailed for an indefinite period in 1993 , but were released after Britain 's National Parole Board ruled that they were no longer a threat to the public .

The British government has so far declined to reveal why Venables had been recalled into custody .

Legal commentator Alan Caplin told CNN police would not have acted lightly given the amount of money the authorities have spent on giving the boys new homes and identities .

`` I think one can surmise reasonably that ... it must be quite serious if there 's some intervention in that reset life , '' he said .

The conditions imposed on the boys on their release banned them from contacting each other , Bulger 's family or from returning to the region of Merseyside , in northwest England , where the crime was committed .

British Home Secretary Alan Johnson told Sky News the reason for the recall would be revealed in time .

`` I believe the public do have a right to know and I believe they will know all the facts in due course , '' he said .

However , British Justice Secretary Jack Straw was quoted in the Times Wednesday as saying it was in the public interest to withhold the details .

`` I have no interest in gratuitously or unnecessarily withholding information , but there are good reasons to withhold it at the moment and that is in the public interest , '' he said .

Venables and Thompson were school boys when they abducted and killed two-year-old Bulger in a crime described by the trial judge as `` unparalleled evil and barbarity . ''

In 1993 , grainy CCTV images showed the boys leading the toddler away from his mother at a busy shopping center in Liverpool , England .

Public anger grew as details emerged of the chilling attack in which the boys tried to drown Bulger before beating him with rocks , bricks and iron rod . His battered body was left on a railway line to be cut in half by an oncoming train .

In November 1993 , after being tried in an adult court , the boys were found guilty of murder and ordered to serve at least eight years of an indefinite prison sentence .

The following year , their minimum sentences were increased to 15 years by then-UK Home Secretary Michael Howard who had received a petition signed by more than 275,000 people in support of life sentences .

However in 1997 , the House of Lords , the upper chamber of parliament , overturned the increase and the boys were freed in 2001 on the condition that they could be recalled to custody at any time during their lives if there was `` any evidence that they present a risk to the public . ''

The boys were given new identities and passports and since 2001 have been protected by an injunction banning publication of their images taken after 1993 , and anything that could reveal their current names and locations .

Both the boys received death threats and it was feared they would be targeted if their whereabouts were divulged .

The first reaction from James Bulger 's mother , Denise Fergus , to Venables ' detention was posted in a Twitter message that read : `` would like to let everyone know jon venables is were he belongs tonight behind bars is this my sons justice . ''

The British parole board will now determine whether Venables should remain in custody or return to the life he has been given since his release from jail .

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Jon Venables back in police custody after breaching conditions of his release

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Venables and Robert Thompson were just ten years old when they murdered James Bulger

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Two-year-old was tortured before his body was dumped on a railway track

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Killers ' release in 2001 after just eight years provoked public outrage